The Iraqi Special Operation Forces (ISOF) struggle to recapture the Iraqi city of Mosul from Islamic State of Iraq and Syria (ISIS) lasted from October 2016 to July 2017, and during that time French filmmaker Olivier Sarbil spent six harrowing months embedded with the ISOF. Here, Here, he tells us the story behind the film he shot while with them, called Mosul, which won him a 2018 Emmy for Outstanding Cinematography: Documentary.

"I started my filmmaking career pretty late – when I was 40," Olivier explains. "After serving as a marine paratrooper in the French Army for three years in the 1990s, I had dedicated myself to my first love: photography." And, by 2011, he'd made the switch to filmmaking. "Before that I didn't really want to move to video because I didn't like the look the cameras were offering," he explains. "But then I managed to get my hands on an EOS 5D Mark II and, for the first time, I realised that you could work with ISO like in photography. You could get moving pictures that looked very photogenic." At around this time, TV news outlets, such as Al Jazeera, began accepting EOS 5D Mark II footage from freelance cameramen. "People were blown away by the look for news pictures. It was totally different and was giving that filmic look. This was how I discovered the world of video."

But his newfound career as a self-taught camera operator was threatened when his right hand was badly injured while covering the Battle of Sirte in Libya. "I was hit by a rocket-propelled grenade," he says. "I was in hospital in France for eight months, had dozens of surgeries and lost part of my right hand." But he wasn't finished with filmmaking – Olivier Sarbil is nothing if not tenacious.

In 2016, Channel 4 News in the UK commissioned him to make a 14-minute film on the battle against ISIS in Iraq (Inside the battle for Mosul), which was longer than his usual three-minute news packages. "I spent six weeks in Mosul and made a film, which was well received," Olivier explains. Then the US TV current affairs programme PBS Frontline contacted him. "They loved the cinematography and wanted me to do a 25-minute piece. After that, they wanted to do a fly-on-the-wall feature film, something more personal with no fixed timeline. That's how I made Mosul."

In an age where most available war footage is either dramatised or hastily captured snippets from fleeing witnesses, Mosul is a towering achievement. It offers immersive insight into modern warfare – unbiased, brutal, and intimate. The 40-minute film focuses on four young Iraqi soldiers – Anmar, Jamal, Hussein, and Amjad – as they fight, and grieve, over nine fraught months. Though never officially affiliated with the unit, Olivier gained an unusual level of access by building a relationship with the unit commander.

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The documentary, which was released in August 2017, was shot while Olivier was embedded with the ISOF during the Battle of Mosul. "I was with them 24/7 – I was sleeping with them, eating with them, going into combat every day," he recalls. "It was very challenging. I was filming for five to six weeks at a time, and then going back and processing the footage in Europe before heading back again. It was an eight-month period, and I spent four or five months on the frontline."

The project was demanding, and Olivier needed a camera that would withstand the punishing fieldwork of the frontline, and the dust of the desert. "Because I shoot handheld most of the time, I need to keep the camera as compact and light as possible," he says. "My Canon EOS C300 Mark II is super robust. When you spend months in a war zone you need something that's reliable. I only had one camera for Mosul – I don't think many other cameras would've been able to last eight months if they weren't as strong or as well sealed as the Mark II."

Originally a Canon-shooting stills photographer, Olivier was drawn first to the EOS C300 and later the EOS C300 Mark II for reasons of familiarity. The fact that Canon's Cinema EOS range is compatible with EF lenses sealed the deal. "I love the ergonomics of the C300 Mark II, and being able to put one prime [lens] or a small 17-55mm lens on it was amazing. I loved working in stills photography, so it was natural for me to use the EF lenses on a video camera… I worked with the C300 for many years and when the Mark II came out, I think I was the first person in France to touch it."

When he was filming in Iraq, there were the obvious dangers of a war zone to negotiate – car bombs, snipers, open gunfire – but Olivier also faced the problem of isolation: working as a one-man crew who didn't speak Arabic. "I didn't have a colleague with whom I could make a risk assessment, or just talk to about the footage. That's very stressful, because sometimes you wonder if you have enough pictures, or the right pictures.

At one point, I could actually see the dirt and dust coming out of the camera fan, but it still worked flawlessly.

"When you're travelling through the desert and the battlefield, there's a lot of dirt and the environment gets smoky," continues Olivier. "At one point, I could actually see the dirt and dust coming out of the camera fan, but it still worked flawlessly." He had to make sure he was equipped to film for at least three days at a time, and knew that cleaning his lenses would be challenging in the dust. He carried five 17-55mm lenses so that he could maintain consistent footage if any of them got damaged. "About 90% of the film was shot with the EF-S 17-55mm f/2.8 IS USM," he says. "It's a budget lens but, since the C300 Mark II is a crop-sensor camera, it's my go-to lens. After getting the lenses properly serviced by Canon on my return, they were as good as new, despite going through a war zone!"

Having little or no access to power meant preserving battery life was crucial to Olivier's shoots. While in Iraq, he rotated five BP-A30 batteries because he found them small and light. He aimed to use no more than two batteries per day, not knowing when he'd next be able to charge them. "When you review your footage is when the battery goes down the most," he explains.

The limitation meant Olivier had to be economical when shooting. "At the end I had maybe 60 hours of footage, and that's not much considering I spent months over there," he says. "I had a limited number of memory cards with me and I couldn't carry lots of hard drives."

One thing Olivier was confident of was the quality of footage he was capturing. "It's capable of delivering beautiful pictures – I've always been impressed by the amazing skin tones achieved with the C300 Mark II and its 15-stop dynamic range," he says. "It's the full package: robust, ergonomic and it helps me achieve the type of look I've visualised."

The video camera also aided his workflow. Olivier had the option of shooting internally up to 12-bit at RGB 4:4:4 in 2K – in comparison to the C300's 8-bit 4:2:2 codec in Full HD – and at 4K internally which, he says, "in terms of codecs gave me more choice to start with." He decided to shoot at Full HD due to the storage space available at the time. "I was doing two backup copies of my raw material every day," he explains, "so I needed to save space because I just couldn't get any more storage.”

During post-production Olivier was involved in every day of the edit with his co-director James Jones. "I'm an editor myself and I shoot film with the edit in mind – I have the arc and an idea of how to build the story already," he says. "That's probably the most difficult part [to grasp] from being a photographer first. You know about composition, etc., but a lot of photojournalists don't know how to build a sequence that works in video."

Mosul's arc is predictably tragic, culminating in death and despair, yet it has no underlying moral, says the filmmaker. "It's more about war's many shades of grey."

The film has certainly resonated with viewers, winning the 2018 Emmy for Outstanding Cinematography: Documentary and other awards. But despite being recognised for filmmaking about conflict, Olivier is not interested in being labeled a war filmmaker. "I'm not a war junkie," he says. "Some people pack their gear and go as soon as a war is starting, but I only go if I have a story to film."

To find out more about Olivier and his work, please visit his website. Please note, some of the content may be considered to be distressing.